Despite the scarcity of computer access, social media use in developing economies has risen at unprecedented rates in the past few years. Thanks to the introduction of smartphones, these mobile-first markets are accessing the Internet with affordable devices at reasonable rates, creating an opportunity for marketers to connect with consumers in countries that have historically been off the digital grid.

The user base in Asia-Pacific is projected to grow by 24.4 percent this year, and more than 40 percent of Twitter users will be in Asia-Pacific by 2018, eMarketer projects. Social media use is growing in Latin America as well—eMarketer expects 227.4 million people to be on social networks by the end of this year, representing more than one-third of the region's total population.

International marketing requires an understanding of the development of the consumer class in each region. Though these countries are often "lumped together" as emerging markets, they're growing differently, Monica Peart, senior forecasting analyst at eMarketer, adds.

In China, the upper middle class is growing so quickly that luxury brands are already in high demand, whereas in India, it's the lower middle class that's growing. "Everyday consumables are much better poised to take advantage of India's new middle class, because purchasing power is not yet to the level of China," Peart explains.

Even within India, however, vast differences exist. Many of the country's wealthy, educated people live in metropolitan areas, so the use of smartphones with powerful features and reliable connectivity is common. In these regions, social media use is "highly sophisticated," and marketers need to keep that in mind, Viswanathan says.

In rural regions, the story is quite different. Though mobile device penetration is high and growing rapidly, devices used there often have limited capabilities and connectivity. As a result, companies such as Facebook are optimizing their messaging and functionality to suit these limitations. The social network has partnered with mobile phone manufacturers to preload its app and give marketers a platform to reach previously difficult-to-target rural audiences. The company also recently launched its Preferred Marketing Developer (PMD) initiative to boost local innovation of digital marketing tools. As of June, it had introduced more than 30 PMD centers in Singapore, Australia, India, and Hong Kong.

While most brands are only starting to deepen their focus on international marketing, some are already answering the call to build more far-reaching campaigns. Among them, Coca-Cola has been using social media to connect with its customers worldwide, creating Twitter handles for dozens of geographic regions. Though the company tweets in English from its central handle, the other accounts send tweets in other languages and share not only general brand messages but also content that's highly targeted for the specific regions.

From its account for the Philippines, Coca-Cola recently tweeted, "What is best paired with an ice-cold Coca-Cola? Pa-deliver na kayo," which translates roughly to "Same day delivery." The company also included the hashtag "openhappiness" and a link to a YouTube clip promoting JollieBee, a local fast-food franchise that serves Coke products and now offers delivery. The tweet serves as an example of Coca-Cola's international marketing philosophy—the content is not only targeted and localized through language or familiar cultural references, but also delivers a brand-consistent message that resonates internationally.

Coca-Cola's Open Happiness campaign, to which the hashtag alludes, relies on the belief that certain concepts, such as happiness, are universal. The campaign culminated during the 2014 FIFA World Cup in June, where Coca-Cola unveiled its happiness flag, a mural featuring more than 200,000 international fan images. Soccer "has an incredible power to bridge social, cultural, and geographical divides," Emmanuel Seuge, vice president of global alliances and ventures at Coca-Cola, said in a statement, "and the Happiness Flag is the perfect illustration of this power, creating a shared experience for people."

As more consumers in emerging economies gain purchasing power and continue to engage with brands on social media, it will be the marketers' job to keep up. Brands such as Coca-Cola, experts agree, are setting a good example.